Diagnosing Alpha-Gal Syndrome

How is Alpha-Gal Syndrome Diagnosed?

Updated 9-21-2017

Considering alpha-gal syndrome(AGS) is relatively new to medicine in the grand scheme of things, diagnosing the ailment can be tricky, to say the least. From symptoms that are easily confused with other more common issues, to a general lack of common knowledge on the subject, doctors are put to the test when called on to recognise this condition. Multiple factors are taken into account when a specialist diagnoses alpha-gal syndrome, some of which we describe below. If you are concerned you may have alpha-gal syndrome, talk to your doctor about finding and seeing a specialist experienced with the condition for definitive answers. Should someone wish to investigate if their symptom set may be alpha-gal related, several options are available to help your doctor make the diagnosis.Disclaimer: We are not doctors, nor medical professionals. If you are experiencing any potentially threatening symptoms of alpha-gal syndrome, be sure to see your family doctor to receive the help you need.

History of Tick Bites

Those who have symptoms that could indicate alpha-gal syndrome should consider asking themselves “Have I been in an environment that could have ticks such as a forest or field with tall grass?” rather than “Do I remember being bitten by a tick?” as a tick need not fully attach to inflict the condition. Minute hatchling ticks barely visible to the naked eye can also bite and cause alpha-gal syndrome, so while the absence of a tick bite does not eliminate alpha-gal syndrome as the cause, the presence of such a bite lends strong evidence to support the diagnosis. Why tick bites lead to the condition remains unclear, but it is well documented that they frequently play a role.

For those who are concerned about recent ticks bites, it is worth noting that alpha-gal allergy symptoms usually take at least 2 weeks to appear. Just because someone has been bitten does not mean that they will develop alpha-gal syndrome, and just because someone was bitten in the past and did not develop it does not mean that they won’t develop alpha-gal syndrome after the next tick bite.

Blood Test

A blood test has been developed to look for igE alpha-gal antibodies by several labs and is a good choice for recently acquired cases, but is not yet approved by the FDA for official diagnostics and may not be covered by insurance as a result. The alpha-gal allergy blood test is different than an allergy blood panel for beef, pork and/or lamb because it is looking for antibodies against the alpha-gal carbohydrate, not the common proteins found in various meats. There is also a blood test for alpha-galactosidase, this is not related to the alpha-gal allergy blood test and is instead looking for a metabolic problem with an unrelated but similarly named enzyme. Be sure your doctor orders the correct test if they are new to investigating AGS as accidental orderings of the wrong test have been reported.

The blood test, when positive, can help clinch a diagnosis, but when negative should not be taken as definitive. Unfortunately, like most allergy tests, the blood test remains imperfect and those who have had the condition for a long time, those who are already avoiding mammal products, and those on certain medications are more likely to show low values on these tests relative to their actual reactiveness. Additionally, those of B and AB blood types may experience more muddled immune responses that can also lead to inaccurate blood test results relative to reactivity. As such, additional tests may be needed in the event of a negative blood test, which ultimately leads some doctors to skip the blood test altogether in favor of other techniques.

The blood test should only be run if a patient has symptoms, since like all allergy blood tests, there is a chance for a false positive.

Food Challenge

While not recommended, another more definitive test known as an oral challenge can be done. This red meat challenge, under the supervision of medical professionals, can verify alpha-gal syndrome in patients who experience clear reactions, but is considered extremely risky and to be avoided unless necessary do to the inconsistent time delay in the reaction. It’s a common myth that alpha-gal reactions are just like those of any other food allergy, and some of the symptoms can be quite dangerous; it is extremely important to note that this test should only be done under the supervision of medical professionals who can intervene and prevent the reaction from becoming lethal if necessary.

When positive, such a test results in the patient experiencing a large clear cut reaction roughly 2-8 hours after eating the meat, so be prepared to spend the whole day at your allergists and to have a massive reaction if going this route. Oral challenges are the gold standard for food allergy testing, but alpha-gal syndrome offers up some additional challenges since reactions are delayed. Individuals with mild AGS may not react to meat consistently leading to a false negative if this test is only done once.

Skin Prick Tests

Traditional skin prick tests against meat extracts are very poor predictors of alpha-gal syndrome and can not be used to help diagnose or exclude it when taken alone. However, a skin prick test against the drug Cetuximab (which cross reacts with AGS) is slightly more reliable, but false negatives can still occur. In general, skin prick tests are not used due to the frequency of false negatives encountered, but when positive for numerous alpha-gal sources can lend a little more evidence for revealing the bigger picture. It is important to note that skin prick tests may be positive even when other type of allergies are at play, so several positive skin prick tests to different mammals is not enough evidence on it’s own.

Food Journal

Another somewhat safer option is to keep a detailed food and symptom journal to get a clearer case history. Experienced allergists may be able to diagnose the condition with just case history and may choose to skip any formal testing if the pattern is clear enough from the beginning. Often they will propose an elimination diet to see if symptoms are alleviated at the same time the journal is begun. An additional benefit of food journals and elimination diets is that they can detect the causal relationship between the consumption of alpha-gal containing products and less clear reaction symptoms over a longer period of time.

Creating a food journal is pretty easy, but requires dedication to be effective. It’s important that each meal (and even snacks) are recorded thoroughly to make sure that everything is fully noted and able to be tracked down the road. Symptoms, even those thought to be unrelated or trivial must also be diligently recorded. Since alpha-gal reactions are typically delayed, pairing a specific reaction to a food entry can be tricky, but an experienced allergist can make short work of finding the characteristic alpha-gal reaction pattern from a well written journal.

Elimination Diet

An elimination diet can not only help identify AGS, but can also be used to determine individual tolerance levels. An elimination diet typically works in one of two ways:

Additive Method: A patient may begin with a diet that’s very restrictive in nature, but slowly adds in foods to test for tolerance and reactions as they go. If reactions persist despite the minimalistic diet, a different minimalistic diet should be tried. Once symptoms end, new foods can be slowly added. This offers the opportunity to start with what you’re sure of and build upon it from there.

Subtractive Method: The subtractive method works in the exact opposite way the additive method does. Proponents of this method start by removing a single food at a time (for instance first mammal meat, then dairy, then gelatin, and so on) until symptoms end.

Those experiencing high sensitivity symptoms such as joint pain or extreme fatigue may need to eliminate all trace sources to find relief, and usually benefit most from the additive method. An additional benefit of the additive method is that it may also uncover other food allergies and intolerances. Those suffering from extreme reactions only may be of lower sensitivity and will find the subtractive method easier to implement. Most doctors will recommend starting with the subtractive method for this reason.

Tolerance Levels

In the end, some people have very low tolerance, while others can tolerate all sources of alpha-gal contaminated food with the exception of fatty meats and organs like beef steak and pork kidney. Some people are highly sensitive and will experience milder symptoms with smaller exposures, while others have low sensitivity and only have large clear reactions or none at all with no inbetweens. About half of patients are high tolerance, low sensitivity reacting only to one or more red meats and not to cross contamination, carrageenan, gelatin, dairy or other trace sources. Someone who was once only reactive to beef may later become reactive to all sources, and someone who was once reactive to all sources may later become less reactive or even fully recover. AGS is highly inconsistent in how it presents over time. The only consistent factor is that their is a delay between eating and a reaction (excluding pork kidney reactions).

Pork-cat Syndrome

It is worth noting that an additional condition very similar to alpha-gal syndrome was described back in the 90s. Pork-cat syndrome should be suspected if reactions seem limited to pork (and rarely beef) products and the alpha-gal blood test comes back negative, or if reactions to red meat happen in less than an hour. Oddly, people with pork-cat syndrome will test positive for allergies to cats, but sometimes do not have clear allergic reactions to pet cats. Instead, they have massive allergic reactions to pork. This is how it got its name.

Unlike alpha-gal syndrome, pork-cat syndrome is caused by a protein (like most food allergies), and reactions occur in less than an hour. At this time, it is thought that pork-cat syndrome is more like a classic allergy with an unusual cross reaction rather than something as unique as the alpha-gal allergy.

It was originally assumed that keeping cats caused the condition, but the allergy is rare outside of Europe lending evidence to the theory that keeping cats is not directly related beyond the fact that doing so may make it worse. It is not unheard of for someone to have both alpha-gal syndrome and pork-cat syndrome at the same time, and early studies frequently confused the two leading to muddled data. Now that both conditions have blood tests, newer data sets are able to avoid this problem by only including patients who test blood positive to the condition of interest.

While diagnosing alpha-gal syndrome still has a long way to go as far as consistency and assurance of results is concerned, progress is being made on a regular and consistent basis; for now, dealing with the symptoms and reactions that result continues to be one of the most difficult aspects of the condition. Fitfunner aims to help create and establish habits that can ultimately lead to easier avoidance of situations that may put you at risk for a reaction, all with the help of a supportive community that’s dealing with similar issues. Keep up to date on the latest news from us to see how you can join in on the experience.